This invention relates to a food supplement, derived from fruit or vegetable fibres, which has beneficial effects for bowel health.
Short Chain Fatty Acids (SCFA""s) are known to have significant physiological effects on the large bowel. In particular, SCFA""s are considered to play a role in the protection against bowel cancer and the development of pathogenic organisms and the development of colonic ulceration and other diseases of the bowel.
SCFA""s (acetate, propionate and butyrate) are produced in the large bowel by microbial fermentation. The benefits attributed to these compounds are variously thought to be the result of either reduced pH or beneficial changes to the molar ratios of acetate, propionate and butyrate or some combination of these. The concentration of SCFA""s, pH and in particular butyrate concentration are putative indicators of bowel health.
More particularly, butyrate is considered to offer protection against bowel cancer. As most intestinal cancers occur in the distal colon, an increased level of butyrate in this region is a key objective in controlling the incidence and development of this type of cancer.
In the processing of fruit and vegetable for consumption, a considerable amount of the fruit or vegetable remains unused because it is either unpalatable or inconvenient to use. This represents a somewhat inefficient use of resources and leads to a waste disposal problem and a loss of potentially valuable resources.
It is also desirable to have a fibre additive for foods that is a substitute, or a partial substitute for ingredients of commonly used foods substances such as flour in bread. Also desired is that these substitutes do not add to the calorific content of the foods, and in many instances that these substitutes do either not contribute flavours at all or at least do not contribute off flavours. A number of examples of fibre food additives are made from waste from fruit or vegetable processing, and one such example is the use of treated citrus albedo for inclusion of a flour substitute in various cereal products such as bread in U.S. Pat. No. 4526794 by Altomare et al.
It is a finding of this invention that the use of a mixture of fibre extracts from two or more types of fruit or vegetables can have a beneficial effect on the large bowel.
Fibre extracts from apple slices and from the albedo of oranges were extracted by a counter current method and added as a supplement to a standard feed for pigs and to a diet for humans. An unexpected beneficial change in indicators of gut health was found when mixtures of the two fibre extracts were used when compared to the use of each fibre extract separately.
The effect is manifest in an increased production of short chain fatty acids in the large bowel, of which butyrate is the fatty acid that is increased to the greatest degree particularly in the distal colon. The experiments conducted to date are suggestive that the physiology of the large intestine is also somewhat modified in so far as the wall of the large intestine is thickened albeit by a statistically not significant amount, indicating that there may be stimulation of growth.
The term fibre in the context of this invention is intended to convey the meaning of material that is substantially indigestible in the small intestine such that it passes into the large bowel of a human or other omnivorous animal species.
It is thus proposed that in a broad form that the present invention could be said to reside in a food supplement, said food supplement derived from fibre extracts from two or more types of fruit or vegetables, the fibre extracts having had a majority of soluble solids removed therefrom.
At present the reason why such combinations of fibre extracts exert their effect is unknown, it is however thought that removal of a majority of the soluble solids is essential for this to have effect. One hypothesis is that insoluble fibre components presented in this way have a more beneficial action in promoting colonisation of beneficial bacteria in the large intestine, thereby acting as a prebiotic.
The removal of soluble solids also has the side benefit of maximising the potential value obtained from the precursor product in so far as it may be possible to sell some or all of the soluble solids. Additionally the insoluble solids that remain are more convenient for food use because they may be dried and hence put into a wider range of foods than would be possible with soluble materials. Insoluble solids from which soluble solids have been removed also have a tendency to be more stable microbiologically and not to produce off flavours, there is also the possibility that any anti microbial substances (that might otherwise adversely affect beneficial large bowel microflora) present in parts of the fruit are also removed.
The two or more types of fruit or vegetable may be selected from the group consisting of grape, citrus, apple, tomato, carrot, mango, papaya, banana, pineapple, kiwi fruit, spinach and melon.
Preferably the two or more types of fruit or vegetables are selected from the group consisting of, grape, orange, apple, tomato, melon, cranberry and grapefruit.
In an alternative form a first of the two or more fruit and vegetables is a citrus fruit and a second fruit is selected from the group consisting of grape, apple, tomato, carrot, mango, papaya, banana, pineapple, kiwi fruit, spinach, melon and cranberry and more preferably the second fruit is selected from the group consisting of grape, apple, tomato, melon and cranberry. In one convenient form the citrus fruit is an orange.
In another alternative form a first of the two or more fruit and vegetables is an apple, and a second fruit is selected from the group consisting of grape, citrus, tomato, carrot, mango, papaya, banana, pineapple, kiwi fruit, spinach, a melon, and more preferably the second fruit is selected from the group consisting of grape, citrus, tomato, and melon.
In one specific form the fibre extracts from two fruits are used, the two fruits being orange and apple.
Citrus fruits that might be used including orange, grapefruit, tangelo, tangerine, lemon, o kinnow fruit and varietals. When dealing with citrus by product parts, citrus xe2x80x9ccupsxe2x80x9d can be used. Cups are halves of the outer portion of citrus fruits comprising the skin (flavedo) and the pith (albedo) and represent the portion of citrus fruit remaining after conventional juice extraction. Preferably the starting material for fibre extraction is a shaved skin, whereby the flavedo has been removed. The benefit of using albedo is that processing is simplified, so that the strongly flavoured portion of the skin is not included.
For pineapples, the xe2x80x9czenithxe2x80x9d solids, which comprise the outer skin and inner core of pineapple can be used. Also whole pineapples can be used.
When papaya is the precursor just the flesh and skin are to be processed. When the seed is included the resultant product has a higher fibre content. Likewise mangos, without seed can be processed.
When a melon is used it might be selected from the group consisting of watermelon, rock melon, honeydew melon or champagne melon.
Without being bound by the same, a possible explanation for the beneficial effects of the combinations of fibre extracts is that the two fibre components each offer different levels of minerals, neutral non starch polysachharides and uronic acids and that a synergy is afforded by a combination of fruits or vegetables having the different levels. Soluble and insoluble neutral non starch polysaccharides, and soluble and insoluble uronic acids provide four possible substrates for microbial growth in the colon. These four possible substrates may result in a series of microbial populations being established along the large bowel, each acclimatised to a preferred substrate and each producing different SCFA""s. In this way, the varying molar ratios of the individual SCFA""s may be explained.
The high level of calcium and other elements are considered to provide beneficial effects on the proliferation of colon cells, the excretion of bile acids and avoiding mineral losses from occurring, for example with diarrhoea. Thus in the case of a mixture of orange and apple fibres, it has been determined that orange is higher in calcium, soluble neutral non starch polysaccharides and total uronic acids than is the apple. Thus it may be expected that the combination of a first fruit or vegetable having levels of one or more mineral or fibre components that are similar to orange and a second fruit or vegetable having levels comparable to apple may provide the synergistic effect. Some typical compositions of fruits are given in Table 1.
Thus in one embodiment of the invention the invention may be said to reside in a food supplement, said food supplement derived from fibre extracts from two or more types of fruit or vegetables, the fibre extracts having had a majority of soluble solids removed therefrom and wherein a first of the two or more fruits or vegetables has:
a calcium content of between 4000 and 15000 ppm;
a soluble neutral non starch polysaccharides content of between 2 and 3 percent dry weight; and
a total uronic acids content of between 20 and 40 percent dry weight and the second of the two or more fruit or vegetables has:
a calcium content of between 200 and 1500 ppm;
a soluble neutral non starch polysaccharides content of between 1 and 2 percent dry weight; and
a total uronic acids content of between 5 and 20 percent dry weight.
Alternatively the invention may be said to reside in a food supplement derived from fibre extracts from two or more types of fruit or vegetables, the fibre extracts having had a majority of soluble solids removed therefrom and wherein a first of the two or more fruits or vegetables has a calcium content of between 4000 and 15000 ppm and a second of the two or more fruit or vegetables has a calcium content of between 200 and 1500 ppm.
Alternatively still the invention may be said to reside in a food supplement derived from fibre extracts from two or more types of fruit or vegetables, the fibre extracts having had a majority of soluble solids removed therefrom and wherein a first of the two or more fruits or vegetables has a soluble neutral non starch polysaccharide content of between 2 and 3 percent dry weight and a second of the two or more fruit or vegetables has a soluble neutral non starch polysaccharides content of between 1 and 2 percent dry weight.
As a further alternative the invention may be said to reside in a food supplement derived from fibre extracts from two or more types of fruit or vegetables, the fibre extracts having had a majority of soluble solids removed therefrom and wherein a first of the two or more fruits or vegetables has a total uronic acids content of between 20 and 40 percent dry weight and a second of the two or more fruit or vegetables has a total uronic acids content of between 5 and 20 percent dry weight.
Preferably the ratio of the first fibre extract to the second fibre extract in the food supplement is between 1:4 and 4:1 and is most preferably between 2:3 to 3:2. In one preferred from of the invention the two fibre extracts are present in equal amounts by weight.
The invention may also be said to reside in a method of preparing a food supplement derived from fibre extracts from two or more types of fruit or vegetables, the method including the steps of removing a majority of the soluble solids from each of the two or more types of fruit or vegetables separately to give fibre extracts from the two or more fruits or vegetables, and combining the fibre extracts to provide the food supplement.
The method may include the steps of slicing each of the two or more fruits or vegetables into substantially uniform pieces, and substantially removing any remaining seed tissue from the fibre extracts after extraction an then combining the fibre extracts to provide the food supplement.
The method may also include the steps of inactivating enzymes within the fruit or vegetable pieces.
The precursor material is preferably undigested, in the sense that it has not been macerated, or treated enzymically, or by other chemical agents such as acid or alkaline to breakdown the structure of the macromolecules forming the fibres. The structure of the plant material is thus still complex. Thus when an apple is prepared for conventional pressing it is first milled, a process in which almost all of the cell walls are disrupted and in fact compounds normally isolated in cell walls or cytoplasm or vacuoles, nuclei etc are homogenised and begin to react. Many of these reactions are enzymically driven such as depolymerisation of pectin or oxidation. On the other hand when an apple is prepared by a preferred embodiment of this invention the apple is sliced, so that the longest diffusion path is no more than say 1.5 mm. Slicing disrupts only a small proportion of cell walls, perhaps 0.5%, and the enzymes and their substrates are kept separate.
The method of preparing fibre also preferably includes the step of inactivating enzymes within the fruit preparation which might conveniently be by heat inactivation. Thus with the example of apple slices after slicing the slices are flash heated to a temperature at which plasmolysis occurs but no heat damage occurs to flavour compounds (60xc2x0 C.). This is termed a critical temperature. The resultant increase in permeability of the (still intact) cell wall increases significantly the rate of transfer of soluble solids from solid to liquid phase.
The majority of soluble solids are then removed from the precursor, by extracting liquids. This is achieved by preparing the precursor material to an appropriate size, for example by slicing to a particle with a thickness of no more than about 2 to 3 mm is found optimal for apple slices, and precontacting the precursor food material with an extraction liquid, and then separating the precursor food material from the extraction liquid, the separation occurring to an extent to give the desired reduction in soluble solids.
This extraction liquid is most preferably water, however, a non-aqueous or non-polar solvent might be used to extract water-insoluble or non-polar compounds. Examples of such solvents are, chloroform, hexane, chlorinated hydrocarbons or acetone. A specific example is the extraction of isoflavones and other flavanoids from orange peel using ethanol as the solvent.
It is preferred that water soluble solids are substantially all removed, in which case the fibre product is substantially free of sugars and other very readily soluble solids whereby greater than 90% of soluble solids are removed. One effect of this is that the fibre product is stabilised against microbial attack. That is not to say that microbial degradation of the fibre is totally inhibited, but rather that this is reduced. Generally fungal growth is not inhibited but growth of the more common food spoiling bacteria are.
Additionally by removal of substantially all of the soluble solids the fibre product has a reduced potential for the development of an off taste, because compounds responsible for flavours have been extracted by the extraction process. Removal of substantially all of the soluble solids is intended to mean removal of substantially all soluble solids that are in a free or unbound state.
A processor suitable for extraction by counter current methods is described in Australian Patent No. 543184. Alternatively other extraction apparatus that could be used include a diffuser made by DeDanske Sukkerfabriker of Denmark and a diffuser made by Amos of Germany. It is anticipated that by use of these processes greater than 90% of the water soluble solids are removed, and more preferably from between 93 to 99%.
The benefits of the invention are expected largely to result by reason of fermentation in the large bowel of non-digestible components of the fruits outlined above, and it is anticipated that less purified forms of the fibres will also have a similar effect to that found for the more purified forms of fibre. It is however not desirable to use conventional techniques of expressing juice from fruit because the supplement will be high in flavours, sugars, and acids. The material is unstable microbiologically and enzymatically and will rapidly develop off flavours and odours and will quickly discolour.
In another form the invention may be said to reside in agent for increasing levels of one or more fatty acids to the colon of an animal or human wherein the agent is derived from fibre extracts from two or more types of fruit or vegetables that have had a majority of soluble solids removed therefrom. Preferably the increased level of fatty acids is greater than the level afforded by any one of the fruits or vegetables alone. Preferably also the fatty acid is a short chain fatty acid which may include acetate, propionate and butyrate. The one or more types of fruit and vegetables may be selected from the group described herein.
It will be appreciated that the invention could also reside in a food product having the food supplement. Suitable food products that may contain the food supplement include, but are not limited to, breakfast cereals, granola bars, soups and beverages including fruit juices. Preferably the food product contains between 1 and 50% by weight of the food supplement and most preferably between 1 and 30%. In the case of liquid food products the upper limit to the amount of fibre supplement that may be added is determined by the viscoity of the ensuing product. Thus, preferably soups may contain between 2 and 15% of the food supplement and beverages may contain between 2 and 5% of the food supplement.
For a better understanding the invention will now be described with reference to a number of examples. It is understood that these examples are only illustrative and are not intended to limit the scope of the invention.